As someone who’s just embarked on their Kubernetes journey and recently earned the KCNA (Kubernetes and Cloud Native Associate) certification, I want to share my understanding of what Kubernetes and the cloud native world are all about.

So GRWM as I explain kubernetes to you!! 🚀

The Monolithic Era and Its Challenges

Before Kubernetes, applications were often built and deployed as a monolith. A typical traditional application sits in a large, single codebase containing all its functionalities – user interface, business logic, database interactions, everything bundled into one big monolith.

The monolithic approach makes it easier to get started and develop at first, but once the application becomes non-trivial, a number of issues begin to appear, especially within large teams.

• Scalability Issues: If one part of the application became a bottleneck (e.g., user authentication), you had to scale the entire application, even the parts that weren’t under heavy load. This was inefficient and often costly.

• Slow Development Cycles: A small change in one part could require rebuilding and redeploying the entire large application, leading to long release cycles.

• Fragility: A bug in one component could bring down the entire application.

As applications grew more complex and user bases expanded, these challenges became significant hurdles. A new approach to deploying applications in a manageable way was needed, enter Microservices.

The Rise of Microservices

Instead of one giant application, microservices break down an application into smaller, independent services, each responsible for a specific function (e.g., a “user service,” an “order service,” a “payment service”).

With the microservices architecture, we can identify parts of our applications or independent services that need more resources and scale them accordingly, helping us save costs. Teams can also work on services independently and deploy them more frequently without affecting other services if a bug is introduced. If one service fails, it doesn’t necessarily bring down the entire application.

Additionaly different services can use different programming languages and databases ensuring the best tool is used to solve a problem and avoiding technology stack lock-in. Microservices allow you to develop your chat service with Nodejs and NoSQL and your video encoding service with much more lower level languages and tools for example.

However, as with every solution in computer science, there are trade-offs. Microservices introduced a new problem: complexity in deployment and management. Imagine having dozens, or even hundreds, of these small services. How do you:

1. Deploy them consistently?

2. Ensure they can communicate with each other?

3. Handle failures and ensure they restart?

4. Scale them up and down based on demand?

5. Monitor their health?

This is precisely the problem Kubernetes was designed to solve.

What is Kubernetes?

At its heart, Kubernetes (often abbreviated as K8s) is an open-source platform designed to automate deploying, scaling, and managing containerized applications. It’s an orchestration system that takes care of the operational complexities of running applications in a distributed environment.

Think of it as an operating system for your infrastructure, specifically tailored for containers. Instead of managing individual servers, you tell Kubernetes what you want your application to look like (e.g., “I want 3 instances of my web server, and they should be accessible on port 80”), and Kubernetes handles the heavy lifting of making that happen.

Why Kubernetes?

Kubernetes addresses the challenges of managing modern, containerized applications by providing:

1. Automated Rollouts & Rollbacks: Deploy new versions of your application with zero downtime. If something goes wrong, you can easily revert to a previous version.

2. Self-Healing: If a container crashes, a node dies, or a Pod stops responding, Kubernetes automatically replaces or restarts them.

3. Service Discovery & Load Balancing: Kubernetes automatically assigns IP addresses and DNS names to your services and can distribute network traffic across multiple instances of your application.

4. Storage Orchestration: It can automatically mount the storage system of your choice, whether it’s local storage, a public cloud provider, or a network storage system.

5. Secret & Configuration Management: Securely store and manage sensitive information (like passwords) and application configurations, injecting them into your containers without rebuilding images.

6. Resource Management: Efficiently allocates CPU and memory resources to your containers, ensuring optimal utilization of your infrastructure.

7. Horizontal Scaling: Easily scale your application up or down by adding or removing containers with a simple command or based on metrics (like CPU usage).

In essence, Kubernetes allows developers to focus on writing code, while operations teams can manage infrastructure more efficiently and reliably.

Kubernetes architecture

Kubernetes operates in a cluster, on a master-worker architecture. A cluster is a logical collection of physical or virtual servers.

• Control Plane (Master Node): This is the brain of the cluster. It makes global decisions about the cluster (e.g., scheduling Pods), detects and responds to cluster events, and manages the state of the cluster. Key components include:

  • API Server: The front end of the Kubernetes control plane. All communication with the cluster goes through the API Server.

  • Scheduler: Watches for newly created Pods with no assigned node and selects a node for them to run on.

  • Controller Manager: Runs various controllers that regulate the state of the cluster (e.g., Node Controller, Replication Controller).

  • etcd: A consistent and highly available key-value store that stores all cluster data.

• Worker Nodes: These are the machines (VMs or physical servers) where your actual applications (containers inside Pods) run. Each worker node contains:

  • Kubelet: An agent that runs on each node in the cluster. It ensures that containers are running in a Pod.

  • Kube-proxy: A network proxy that runs on each node and maintains network rules, allowing network communication to your Pods from inside or outside the cluster.

  • Container Runtime: The software responsible for running containers (e.g., Docker, containerd).

You, as the user, interact with the API Server (usually via the kubectl command-line tool) to tell Kubernetes what you want. The control plane then works behind the scenes to ensure your desired state is achieved and maintained across the worker nodes.

What Even is Cloud Native

Kubernetes is a cornerstone of the Cloud Native ecosystem. “Cloud Native” is an approach to building and running applications that takes full advantage of the cloud computing model with an emphasis on cost-efficiency, reliability and faster-time-to-market. It’s about more than just running apps in the cloud, it’s about how you design, build, and operate them.

Key principles of Cloud Native include:

• Containerization: Packaging applications and their dependencies into lightweight, portable containers (like Docker).

• Microservices: Breaking down applications into small, independent services.

• CI/CD (Continuous Integration/Continuous Delivery): Automating the software delivery process from code commit to deployment.

• DevOps: A culture and set of practices that integrate development and operations teams to improve collaboration and efficiency.

• Orchestration: Using tools like Kubernetes to automate the deployment, scaling, and management of containers.

Systems built on the cloud-native architecture usually have some of the following characteristics:

• Automation: CI/CD pipelines, bash scripting, IaC etc
• Self-healing: health checks, automatic restarts
• Scalability: auto-scaling, load balancing
• Cost efficient: scaling down during low activity
• Maintainability: microservices
• Security: network rules, container isolation

The Twelve-Factor Methodology is a good place to learn cloud native principles.

The goal of Cloud Native is to build resilient, scalable, and observable applications that can be deployed quickly and reliably in dynamic, modern environments.

What’s Next After KCNA?

Getting your KCNA is a fantastic first step! It shows you understand the foundational concepts of Kubernetes and the cloud native landscape. But as with anything in tech, hands-on experience is key.

That’s exactly why I’ve embarked on a 10-week Kubernetes project challenge. Each week, I’m tackling a new, practical deployment or concept to deepen my understanding. This is where the real learning happens, by getting your hands dirty and seeing how these concepts apply in real-world scenarios.

And there’s so much more to explore! From networking and security to advanced scheduling and serverless functions, the Kubernetes world is vast and exciting.